Osteosarcoma cancer is one of the most lethal malignancies, and there is no effective preventive measure to date. Chamaejasmine is the major ingredient in Stellera chamaejasme L. Except its potent pain-relieving efficacy as reported, chamaejasmine also exerted its anti-tumor activity in several tumor models. Here, we reported that chamaejasmine had a profound anti-proliferative effect on human osteosarcoma cells in a concentration-dependent and time-dependent manner, which was associated with an increase of p21 and bax and a decrease of bcl-2 and consequently increased caspase-3 activity. The main mechanism of anti-tumor potency was mainly attributed to the induction of p53. Chamaejasmine hugely elevated the expression of p53. The results of p53 shRNA experiment further demonstrated that p53 knockdown severely impaired the sensitivity of tested cells to chamaejasmine, implicating the important role of p53 played in chamaejasmine's anti-tumor activity. In conclusion, results showed chamaejasmine induced apoptosis in MG63 cells and could be a candidate drug for osteosarcoma cancer chemoprevention.